1. Field of the Invention
The present invention relates to an optical receiver which converts an optical signal fed into a photodiode to an electric signal.
2. Related Background Art
FIG. 14 shows a basic configuration of a conventional optical receiver. An optical signal OS is converted into its corresponding electric signal by a photodiode 1. Thus formed photocurrent is converted into a voltage signal by a preamplifier (transimpedance amplifier, current-voltage converter circuit) 3 comprising an amplifier 3a and a transimpedance 3b, and the resulting signal is transmitted to a data-identifying/reproducing and clock-extracting circuit 4.
It is often necessary for the conventional optical receiver to monitor an average input light intensity. Though the average value of the photocurrent generated in the photodiode has to be detected therefor, no circuit for this purpose can be inserted in the anode of the photodiode 1. This is because the preamplifier 3 is connected to the anode of the photodiode 1 and, consequently, another circuit element connected thereto would deteriorate waveforms of signals, in particular, in high-frequency bands used for optical signal transmission.